<!DOCTYPE html>
<select size=20>
  <optgroup label=group id=group>
    <option>apple</option>
    <option label=banana></option>
  </optgroup>
  <option label=cherry></option>
</select>

<script>
var group = document.getElementById('group');
group.appendChild(new Option('durian'));
var nestedGroup = document.createElement('optgroup');
nestedGroup.label = 'nested';
nestedGroup.appendChild(new Option('fig'));
group.appendChild(nestedGroup);
</script>
